Current mobile phones can remove a battery from the casing thereof and replaced it with an auxiliary battery, if the amount of electricity charged in a battery becomes insufficient.
FIG. 7 illustrates an exemplary known mobile terminal apparatus. A mobile phone includes a rear case 1 constituting a casing, a battery 3 to be accommodated in a recess 2 on the back face of the rear case 1, and a lid 4 that covers the battery 3 from the side opposite the recess 2 and that is engaged with the rear case 1.
The known mobile terminal apparatus can reduce the thickness of the casing as a result of omitting a partition of the recess 2 for separating an internal space of a front case to be engaged with the rear case 1 from an accommodation space for the battery 3.